The invention relates generally to electric machines, and more particularly, to electric machines such as spoke-type Internal Permanent Magnet (IPM) machines and Synchronous Reluctance machines and a design configuration that effectively addresses torque ripple.
Torque ripple in electric machines, such as spoke-type IPM and Synchronous Reluctance machines, is a concern. Lower torque ripple leads to lessened transient losses in the electric machine as well as smoother reaction to electrical torque inputs.
One technique in reducing torque ripple is by stator shifting by the slot pitch. While this procedure helps reduce torque ripple, the procedure can place unwanted stresses on the insulation material in the slots as well as reducing the torque content in the machine. Stator shifting or stepping over the axial direction creates sharp edges which can cut in to the slot insulation, ultimately affecting the robustness and reliability of the electric machine.
Therefore, it is desirable to improve upon current designs in electric machines, such as spoke-type IPM and Synchronous Reluctance machines, to effectively reduce torque ripple.